Coolers for rotary kilns



March 24, 1970 F. E. JENSEN 3,502,311

COOLERS FOR ROTARY KILNS Filed May 15, 1968 2 Sheets-Sheet 1 FIG. 1

INVENTOR FLEMMING EDVIN JENSEN ATTORNEYS United States Patent 3,502,311COOLERS FOR ROTARY KILNS Flemming Edvin Jensen, Copenhagen-Valby,Denmark, assignor to F. L. Smidth & C0., New York, N.Y., a corporationof Delaware Filed May 15, 1968, Ser. No. 729,275 Claims priority,application Great Britain, May 17, 1967, 22,877/67 Int. Cl. F02m 37/ 00US. Cl. 263-32 6 Claims ABSTRACT OF THE DISCLOSURE An improvement inrotary kilns of the type having a number of cylindrical cooler tubesmounted around the outlet end of the kiln with their axes generallyparallel to the axis of the kiln. The inlet end of each tube isconnected to an outlet of the rotary kiln by a supply chute throughwhich material to be cooled enters the cooler tube. The improvement isin the inlet end of each supply chute which is formed by a sleeve havinga heatresistant lining. The sleeve is inserted from the outside of thekiln into an outlet in the wall of the kiln and extends through the kilnshell to the interior surface of the kiln lining. This constructionreduces wear on the supply chutes and permits ease of replacement of anyWorn parts.

BACKGROUND OF THE INVENTION This invention relates to coolers formaterial burnt or sintered in a rotary kiln, specifically to that typeof cooler with comprises a number of cooler tubes mounted around theoutlet end of the kiln with their axes parallel or substantiallyparallel to the axis of the kiln. Each cooler tube has an inlet at oneend of the tube and an outlet at the other end, the inlet end of eachtube being connected to an outlet of the rotary kiln by a supply chutethrough which material to be cooled enters the cooler tube. Cooling airdrawn or blown through each cooler tube passes as preheated secondarycombustion air through the same chute to the interior of the kiln.

The cooler tubes are commonly arranged symmetrically around the kiln andmay be parallel or inclined at. a slight angle to the axis of the kiln.To further the heat exchange in the cooler tubes and to assist inpassing the material from the inlet of the cooler tube to its outlet,special devices, such as lifters, scoops, or chains, are often providedinside the cooler tubes. The cooler tubes may extend from their inletseither upwards towards the inlet end of the kiln or downwards away fromthe inlet end of the kiln.

During rotation of the kiln the material being burned or sintered liesmostly to one side of the central diametral plane, advancing in arolling and sliding motion down through the kiln. The material passesout of the kiln through the outlet holes as the kiln rotates, and aseach outlet hole comes to the bottom of the kiln. Due to the rotation ofthe kiln the material will not fall straight through the outlet holesbut fill hit the wall of the supply chutes linking the kiln to thecooler tubes. Cement clinker, and similar materials processed in thekiln are very hard and tend to wear away the supply chutes and thecooler tubes. Furthermore as the material processed in the kiln is veryhot when it leaves the kiln, the supply chutes to the cooler tubes areheated by the material to a high temperature, and this reduces theirresistance to abrasion, thus increasing the rate of wear. For thisreason the supply chutes have to be frequently replaced, and thusinvolves considerable loss of production during the shut-down of thekiln necessary for maintenance.

To reduce or prevent this wear it has previous y been 3,502,311 PatentedMar. 24, 1970 proposed to provide chutes having an inclination to thekiln shell corresponding to the direction of the stream of materialfalling through the outlet holes so that the material falls freelythrough the chutes without hitting the Walls. Although some reduction inwear can be achieved in this way, the reduction is only obtained whensmall amounts of material are being processed. When production isincreased and larger kilns are used, it is ditficult to maintain andcontrol a constant stream of material through the outlets and thematerial will then fall through the holes in random directions. In anycase, inclined chutes are rather complicated to make and mount on thekiln.

It is the object of the present invention to provide a rotary kiln witha cooler in which the wear on the supply chutes is reduced to a minimum,and in which the construction of the chutes is such that it is possibleto replace any worn parts simply and quickly.

SUMMARY OF THE INVENTION According to the invention, the inlet end ofeach supply chute is formed by a sleeve having a heat-resistant lining,the sleeve being inserted from the outside of the kiln into an outlet inthe wall of the kiln and extending through the kiln shell to theinterior surface of the kiln lining. The inlet sleeve may then beconnected directly to the cooler tube, or there may be an intermediatesleeve also with a heat-resistant lining between the inlet sleeve, andthe cooler tube. In such constructions, the inlet sleeve or theintermediate sleeve or both can easily be rep aced from the outside ofthe kiln.

The preferred form of heat resistant lining is one made of ceramic,since this is more resistant to wear at high temperatures than is aconventional brick refractory lining and can also be pro-formed andinstalled as a whole. Preferably the lining or linings are in the formof a monolithic tube of ceramic, and such linings are not only simple toreplace, but also strengthen the sleeves they are lining; alternativelythe linings may be made up from several parts, for example formed fromringlike sections packed one on top of another in the sleeves.Refractory linings, particularly those of ceramic, are brittle,especially at edges and corners, and the ends of the linings of thesleeves should thus preferably be protected by means of annular steelrings mounted in the sleeves at either end of the lining; such ringsserve also to strengthen the sleeves and to locate and retain thelinings in the sleeves.

The inlet sleeve should preferably be formed with one or more axialslits in its surface at the end which extends into the kiln; this willallow for expansion of the lining at the hot end of the inlet chutenearest the interior of the kiln.

Advantageously the inlet sleeve is conical, its diameter decreasingtowards the interior of the kiln. In this way there is less danger ofthe sleeve becoming jammed in the kiln wall by processed materialpacking around it. Clearly one part of the lining will receive the mostwear, and it is thus desirable that the inlet sleeve be mounted on thekiln in such a way that it can be rotated about its axis to a freshposition, this exposing unworn lining to the abrasion of the materialfalling from the kiln. In this Way the overall life of the lining can beprolonged. If the sleeve is conical, then such rotation is facilitated.

The cooler tubes are normally rigidly mounted on the kiln, and provisionfor heat expansion must therefore be made in the supply chutes. Asuitable expansion joint must be made between the kiln and each coolertube, or between the kiln and each intermediate sleeve, to allow forexpansion of the chute in length as well as in diameter, designed insuch away that no material may escape through it. This may be done byincorporating suitable heat resistant packings in the joint. Preferablythe joint is provided between the kiln and the intermediate sleeve,where material does not accumulate; this is found to be more eflicientthan forming the joint at the inlet end of the cooler tube itself.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view partly in sideelevation and partly in central section of the discharge end of acombined rotary kiln and cooler combination.

FIG. 2 is a longitudinal section through part of a rotary kiln, showingan outlet of the kiln, the inlet end of a cooler tube and the chuteconnecting the outlet with the inlet end of the cooler tube, and

FIG. 3 is an enlargement of part of FIG. 2, showing in detail alongitudinal section through the mounting of the inlet sleeve, theconnection between the sleeve and the kiln, and the expansion joint.

DESCRIPTION OF THE PREFERRED EMBODIMENT The discharge end of a combinedrotary kiln and cooler apparatus is shown wherein a rotary kiln 11comprises a shell 12 and a refractory brick lining 13. One outlet fromthe kiln is shown through a flanged pipe stud 14. The outlet through thepipe stud 14 leads to a cooler tube 15 through a supply chute 16,comprising an inlet sleeve 17 having a monolithic ceramic lining 18 andan intermediate sleeve 19 having a monolithic ceramic lining 20. Thecooler tube 15 is provided with a refractory brick lining 21.

The ceramic lining 18 is held in position in the inlet sleeve 17 bymeans of annular steel rings 22 in the ends of the sleeve, these ringsprotecting the ends of the ceramic lining from impact on them of thematerial in the kiln. The sleeve 17 has a flange 23 (FIG. 3) and is heldin position in the pipe stud 14 by a ring 24 bolted to the stud; it isalso formed with longitudinal slits 26 to allow for expansion of thelining nearest the interior of the kiln. An expansion joint is providedby means of a sealing ring with grooves 27 and 28, in which heatresistant packing material 29 is embedded, thus allowing forlongitudinal or diametric expansion of the intermediate sleeve.

When the pipe stud 14 is approximately in the position shown in thedrawing, that is at its lowermost position, material processed in thekiln 11 will pass through it and the supply chute 16 to the interior ofthe cooler tube 15. As the kiln rotates the cooler tube rotates togetherwith it, and the material is conveyed by gravity through the cooler tubefrom the inlet end to the out let end, the discharge end of the kilnshown in FIG. 1 being at a lower elevation than the opposite or infeedend for the raw material. Cooling air is drawn or blown through thecooler tube and passes into the kiln through the supply chute incountercurrent to the stream of material.

The material passing into the chute hits the walls of the chute,generally in one specific area, but the ceramic linings 18 and 20 resistthe abrasive effect of the hot material.

As the inlet sleeve 17 recessed in the pipe stud 14 is tapered towardsthe interior of the kiln, it is easily detachable, even when the spacebetween the sleeve and the brick lining 13 or between the sleeve and thepipe stud 14 is filled with dust. Consequently, the sleeve 17 may beloosened and turned about its own axis so that the wear on the lining 18may be distributed over the whole of the circumference. The whole sleeve17 with lining 18 may also be replaced completely in one operation. Suchof the two rings 22 as are flush with the kiln lining 13 may be equippedwith a transverse rib (not shown) serving to prevent clinker lumps toobig from passing into the supply chute 16.

I claim:

1. In a rotary kiln of the type having a number of cylindrical coolertubes mounted around the outlet end of the kiln with their axes parallelor substantially parallel to the axis of the kiln and the inlet end ofeach cooler tube connected to an outlet of the rotary kiln by a supplychute, the improvement in combination therewith comprising an inlet endof each supply chute formed by a flanged sleeve having a heat-resistantlining, the sleeve being inserted from the outside of the kiln into anoutlet in the wall of the kiln and extending through the kiln shell tothe interior surface of the kiln lining, the inlet sleeve being conicaland the lining thereof being in the form of a monolithic conical tube ofceramic.

2. In a rotary kiln of the type having a number of cylindrical coolertubes mounted around the outlet end of the kiln with their axes parallelor substantially parallel to the axis of the kiln and the inlet end ofeach cooler tube connected to an outlet of the rotary kiln by a supplychute, said supply chute comprising an inlet sleeve and an intermediatesleeve, each of said sleeves being of steel, the inlet sleeve beinginserted from the outside of the kiln into an outlet in the wall of thekiln and extending through the kiln shell to the interior surface of thekiln lining, the lining for said supply chute being formed of severalring-like sections of ceramic packed one on top of another in the twosleeves.

3. A kiln according to claim 2 in which an expansion joint is providedbetween the kiln and the intermediate sleeve.

4. In a rotary kiln of the type having a number of cylindrical coolertubes mounted around the outlet end of the kiln with their axes parallelor substantially parallel to the axis of the kiln and the inlet end ofeach cooler tube connected to an outlet of the rotary kiln by a supplychute, the improvement in combination therewith comprising an inlet endof each supply chute formed by a flanged sleeve having a heat-resistantlining, the sleeve being inserted from the outside of the kiln into anoutlet in the wall of the kiln and extending through the kiln shell tothe interior surface of the kiln lining, the sleeve lining beingprotected and located and retained in the sleeve by annular steel rings.

5. In a rotary kiln of the type having a number of cylindrical coolertubes mounted around the outlet end of the kiln with their axes parallelor substantially parallel to the axis of the kiln and the inlet end ofeach cooler tube connected to an outlet of the rotary kiln by a supplychute, the improvement in combination therewith comprising an inlet endof each supply chute formed by a flanged sleeve having a heat-resistantlining, the sleeve being inserted from the outside of the kiln into anoutlet in the wall of the kiln and extending through the kiln shell tothe interior surface of the kiln lining, the sleeve being formed withone or more axial slits in its surface at the end which extends into thekiln.

6. In a rotary kiln of the type having a number of cylindrical coolertubes mounted around the outlet end of the kiln with their axes parallelor substantially parallel to the axis of the kiln and the inlet end ofeach cooler tube connected to an outlet of the rotary kiln by a supplychute, the improvement in combination therewith comprising an inlet endof each supply chute formed by a flanged sleeve having a heat-resistantlining, the sleeve being inserted from the outside of the kiln into anoutlet in the wall of the kiln and extending through the kiln shell tothe interior surface of the kiln lining, the inlet sleeve being conicaland so mounted in the kiln that it can be rotated about its axis to afresh position.

References Cited UNITED STATES PATENTS 1,652,168 12/1927 Fasting 263321,653,050 12/1927 Lindhard 263-32 2,845,259 7/1958 Henrichsen 263-32JOHN J. CAMBY, Primary Examiner

